At least 55 people, including 11 women and three security personnel, were killed and nearly 200 injured when a suicide attacker detonated a powerful bomb at Wagah in Pakistan Sunday, minutes after the popular flag-lowering ceremony at the hugely symbolic and main land border crossing with India.

“A large number of people were returning after watching the Rangers flag ceremony at Wagah border when a suicide bomber blew himself up near one of the exit gates,” Inspector General of Punjab Police Mushtaq Sukhera said.

Three Pakistani Rangers were among the dead. “The Rangers had made stringent security measures but it was difficult to check suicide bomber,” he said.

According to Sukhera, the bomber appeared to be in his early 20s and was carrying 20 to 25 kilograms of explosives with him, some of which was hidden inside his jacket. He said the suicide bomber was stopped at the gate of the parade ground and detonated the bomb right when people gathered near the gate.

Al-Qaeda affiliated militant group Jandullah, which was behind a suicide bombing that killed at least 78 Christians at a church in Peshawar last year, claimed responsibility for the attack.

The spokesman of the splinter group of the Tehreek-i-Taliban Pakistan Ahmed Marwat said the attack was a reaction to military operation Zarb-i-Azb and Waziristan operation.

Defence Minister Khawaja Muhammad Asif expressed the government’s resolve to fight terrorism in the country. In a statement, he said the terrorists cannot dent the resolve of the nation to fight terrorism, Radio Pakistan reported.

In New Delhi, Prime Minister Narendra Modi condemned the attack, calling it “shocking” and “a dastardly act of terrorism”. He offered condolences to the families of the dead and sent prayers for the injured.

Huge crowds gather every evening at the Wagah crossing, 22 kilometres from Lahore, to watch a “lowering of the flags” ceremony and witness the energetic display of military pageantry that accompanies the closing of the border post which soldiers from both countries have conducted for decades at this crossing.

Earlier reports had said it could be a cylinder blast.

In the wake of Muharram, the police had made strict security measures. “We had reports that some banned outfits might target Shias, religious personalities, public processions and important buildings,” Sukhera said.

Imdad Husain, an eyewitness, told reporters that he was returning after watching the parade ceremony when he heard a huge explosion near the market. “I fell unconscious. When I gained consciousness, there was complete darkness. Many injured and I cried for help, lying on the road. After 15 minutes, some rescue men came towards me and shifted me to Ghurki Hospital,” he said.

Samina Bibi was returning with her husband and two young children when the blast took place. On a bed of the Ghurki Hospital, she was crying and asking doctors about her husband and children. “The doctors were comforting her saying they are alright,” Imdad said.

Emergency has been declared at all hospitals in Lahore. Punjab Emergency Services Rescue 1122 spokesman Jam Sajjad told PTI that 50 people had been killed so far and feared the death toll could rise. “We have shifted about 200 injured in different hospitals of Lahore,” he said.